Cancer is the second leading cause of death in the United States, accounting for one in every four deaths. This year, it is expected that over 1500 Americans will die of cancer each day and that a million new cases of cancer will be diagnosed. The most common treatments for cancer are surgery, radiation and chemotherapy. According to the American Cancer Society, immunotherapy can be considered as the “fourth modality” in the treatment of cancer. Immunotherapy is treatment that stimulates one's own immune system to fight cancer.
Cancer is a group of diseases characterized by uncontrolled growth of abnormal cells of the body. All types of cancer involve the malfunction of genes that control cell growth and division. Some of these genes become incorrectly regulated, resulting in over- or under-production of a particular protein, while others become mutated, resulting in unusual or abnormal proteins that alter normal cellular functions. These abnormal proteins, referred to as “tumor cell antigens,” should be recognized and destroyed by an individual's immune system as “foreign” antigens.
However, the immune system of a cancer patient may ignore these tumor antigens and be unresponsive to the growing tumor. Using immunotherapy approaches, such as cancer vaccines and immune system modulators, an individual's immune system can be induced to mount a potent immune response against tumor cell antigens, resulting in elimination of cancer cells. A cancer vaccine can contain a tumor cell antigen that stimulates the immune system to recognize and destroy cells which display that antigen. Treating an individual with such a cancer vaccine can result in a humoral response, which involves producing antibodies that recognize and target tumor cells for destruction and a cellular response, which involves producing cytotoxic T cells that recognize and destroy tumor cells directly, or both responses. It can be desirable to obtain both a humoral and cellular immunity response during immunotherapy because both arms of immune response have been positively correlated with beneficial clinical responses. To help stimulate either or both humoral and cellular immune responses, a cancer vaccine can be combined with an adjuvant, which is a substance that stimulates a general immune response.
The potency of cancer vaccines is greatly enhanced by the use of adjuvants. The selection of an adjuvant for use with a particular vaccine can have a beneficial effect on the clinical outcome of vaccination. Some vaccines are ineffective in the absence of an adjuvant. Effectiveness of a vaccine may be particularly troublesome when the vaccine is produced from self antigens such as those required for cancer vaccines or other non-infectious disease vaccines. In view of the beneficial effects of adjuvants in vaccine formulations, it is surprising that only one type of adjuvant, aluminum-salt based adjuvants, are currently in wide use in United States-licensed vaccines.
Thus, there exists a need for more and improved immunological adjuvants. The present invention satisfies this need and provides related advantages as well.